How many can be used at once?

[fab10]

After trying to listen to UMS once a night and DRS once a morning I've learned better.  Don't try to make two kinds of shields work together.

I'm now committed to using DRS to the exact letter per the instructions.  Even so, I'm wondering if there is any way to fit something in that is geared towards success or money. Is there anything else that can be used during the 7 days off part of DRS? Or do I truly need to listen to this 1 sub only for the next 3 months?

Days off are meant to be days off

However, if really necessary you can mix DRS with some subs that do not have a shield. Or you can use a newer sub that contains DRS. In both cases you will split the attention so you could get a little less results compared to a stand-alone. If in doubt about a specific combination, ask Shannon. 

E.g. - Back then Shannon told me I could mix E3 and DRS. Or you could now use E4 that contains DRS.